Rotary pump



Feb. 11, 1958 w. P. SCHIRMER ET AL 2,822,760

ROTARY PUMP Filed Oct. 5, 1953. 2 Sheets-Sheet 2 INVENTORS WALDO p. SCH/QMEQ d? E/CHAED 4- KNAUS United Sta ics Patent 1 ammo. ROTARY PUMB Waldq P. Schirmer, Clea elnnd andJfichardtA, Knaus,

This invention relates to rotary vp un p s. aclapted for handling all nianner of fiuids and rnoreparticul a r lylto gear puinps'having a driven rotor and n idler rotor,

The preferred ernb odiment of my inventl s a ro a l'p q' p ha n as n w r nvm t ea q and an inner driven idler gear ecceutricallyl mountedgwith respect to" the outer gear in intern e shing relation therea h et h tu on' t I Oy m nt1Q ;fih gears, fluid is drawn into the ca singand through the teeth 'of'the outer gear, the fluid hayingits pressuretincreased by the sealing action of the intc'rrneshing teeth, and is finallydischarjged at an increased pressure fron the'cas'ingQ The sealing action of theteeth is obtained in a h bmhpn he e ea i -9 3. i ta least 1 6f h e h utsrfl ea -w t nue ous ly. rhe'pum gag action is further enhanced by ,hav: ing the teetho f thefouter gear spaced in order that fluid may passiradiallvtherebetween, thus reducingthe frictionand the'dis ta'nce which the vflui'drnust travellinternal;

ncr rotor are iso shaped for complemental engagement that a 'mininiumofspacerernains whenthe teeth are full'yengag'ed: This is accomplished by providing a tooth, shape on'the idler rotorwhich .will allow the to'oth to extend toith e periphery of the outer gear.

hams st n q fiam bis t of thi in en n e foreQ'is to provide a rotary pun phavinga minimum of.

parts jin frictional engagement. and having purnping elements which aredurable and rugged and n a'y be n anu facturd inexpensively without. elaborate machining opaq hst O e t i inYI tiQn .t Pr v de. a ro ar P p ia friction which results in an increase in capacity and efr- A- further object of this invention is to provide are tary purnp of the gear type having an outer gear andan inner idlergear arranged in such a manner that the crescentcommonly used with this construction is notrequired.

A still further related gears-with circular tooth forms whichmaterially lowers the cost of manufacture and increases the degree:

with consequent im:

of. accuracy which can be maintained provcment of efiiciency-and wear-lif Other. objects,.features and advantages of the invention will become apparent from a consideration of the following detailed specification taken in connection with the accompanying drawings, in which:

Figal is an end view of a pump ernbodying rny invention with partsremoved for purposes of clarity;

object of this invention is to provide .r Fig 2 is: a longitudinal @sectional view taken along r 2,822,760 r .Bhtentedi-Eebh11,1955

Fig., 3 is a fragmentary end,-viewwsimilaryto-Jig 1. showingdhe gears in a differentirelative.positionaand;

Fig In .a detail; view, of the outeripumping; gear a and h fl. fa ss y- Ra /w n g r ts gsnd pu p. 1 m ody n my invention istshownrj therein, having a hollow casing 10. Aicylindrical :cavity 12,,is forrnedjn thevcasing lfl having, its; centerline;tconf orrning to the? generalof the. v casing10l An inlet port 14.:andv-an -out let:port-16 are located in the casing 10..and each have one end; opening into;thercavity,12and the other endtopening ex ternal ly of thet purnp ;.casing for; connectionwto the-msual piping syst A; flange f 18 having a plurality of bolt holes 2tl is proyided .on thercasing ltkfor aflixing a ;con panion flangflandpiping thereto;

' Aim pi i ca t r uter l smountedz v or a iong'wifli a i y,-g with e per ph y ot-lhesear 22- in ,.sli,d gecontact with the -wall of thc,;cavity :12. A pluralit eeth,24 ,=are formed on'agear; disc 26 andezjritend ax ally or longitudinally relative to;the--di s c 26; The, meme; ee h Mor pac d ap r vpro di st-tin. r tticest ort he assa a-o u t w ent heear r u r at a lhas e peara e f a,-distc-t ke.-.w eel with finger-like teeth extending; laterally therefrom,- the est a a n ei in vd; o; he h e m outer: l mits; f

the disc 2a The .teeth 2Q have-inner-circulaksutfa es shapcd a s ar cs of circles of-constant radius on the;;po tionfof thet teethgld not adjacent hewall; of the;;cayity 2; e ltfa e zac n hee t r ota iono dhe gear 22. The outer; surfacespf the outer rotorwhich are i d iacen f e cy indr ca sur ace fa e in which forms ga -wall of; cavity- 12 are; constructed and ;arranged; to rotate in. sealing contact relative theretoa An idlerge ar; on inner rotor 28 ;-having a, =plurality pf: teeth ,3!) is mounted for rotation in the pump cavity- 12. eeth 0' l r ar fit ea orm d y ng n o v x: and concave surfaces 34-and32, Gear 28 rotatesabout-g a center; which is eccentric relatiye to the center; of,;ro.-,- tation offlthe gear 22. The axispf rotatiomof iinnertroa tor .28; is; disposed; along an imaginary: line v 15 extending: throughthet axis of rotation, of outer rotor ;22- and-the; center of thedividing wall llgbet ween ports 14 andl16t; The centers of the respective t gearsare displaced, atdistanc e of -one-half of the 5;height;:of the tee th -;24.zv The. outer wall 32 orconcavet surfaces 0f the-gear. 28 'be. tween the convex; surfaces .34 of teeth 30 is formed with a circular surface having a;radius complemqntaryt'tonthe. outersurface of the -teeth- 24, More particularly;;.con-,; cave surfaces 32 -of innerrotor.teeth-;30 are;shape d-=as, arcs of circles having a constant radius Thelinner-cir cular, surfaces of outer rotonteeth 24.-are.-shape d as,- circles having a radius .of. curvature slightly les s than the: radius of curvature of circular concave surfaces;;32 of. inner rotor teeth 30.

The teeth 30 onthe idler gear,.28 have .a ;length;which allows themto extend Io-theflwall of the cavity 12 be-,. tween the teeth 24at theaforernentioned imaginary line- 15 .in tangency. with and-between apair of outer rotor teeth24tin sealing contact viding wall 11 which end is contiguoustto Ycavity. 12.;

h mi s inner ro r v fitlr isp ac ma muma posed between ports .14 and 16, th e thickness .of the dip viding wall ll is, for example, rnade less than the.1;di s; i

m. tw n u err lthiz t l lqneJhe c i drical. Thetidler gear 28 ,must neces t r c o t e avi MZ-p san'lyhave one less tooth than the outer gear 22 since w h. the nn d 1 1 of) is-v 11 and to seal inlet port 14 from-out a when inner rotor teeth 30are dis -v,

an idler gear tooth moves from the space between the teeth on the outer gear to an adjoining space during one revolution of the outer gear. To maintain the seal between the teeth on the gears without the use ofa crescent boss or similar structure, it isnecessary that the :idler tooth he in constant-engagement with one of the outer gear teeth. Accordingly, theends 34 of the teeth 30 on the idler gear 28 are shaped in s uch'a way that as the teeth move relative to each other; they are constantly in contact with the adjacent teeth 24Jonthe outer gear 22. Ends 34 are accordingly shaped .as arcs of circles having a constant radius. This produces a sufficient seal ing contact which effectively seals against the passage of fluid between the teeth and results .in the formation of expanding and contracting pockets-between the teeth. This-complemental shape of ends 34 of teeth 30 in conjunction with the aforementioned displacement of the centers of inner rotor 28 and outer. rotor 22 cooperate to cause inner rotor 23 to have everyone of its teeth 30 in sufiicient contact with at least one of teeth 24 upon outer rotor 22 at all times to maintain an adequate seal between the spaces between the teeth and between inlet port 14 and outlet port 16 about the longer path around the peripheries of rotors 22 and 30. In Fig. 1, the gears are shown with one of the teeth 30 extending to the wall of the cavity 12. In Fig. 3, the gears are shown with the complemental circular surfaces on the teeth 24 and the gear 28 in contact.

The casing has a head 36 mounted on one end thereof for closing one end of the cavity 12 after the pumping gears 22 and 28 are in place. A bore 38 is formed in the head 36 having its centerline displaced from the centerline of the cavity by the amount of the eccentricity existing between the gears 22 and 28. A pin 40 is mounted in the bore 38 and extends into the cavity 12 to act as idler shaft for the gear 28. A bushing 42 is aifixed to the gear 28 and functions as a bearing on the surface of the pin 40 as the gear 28 rotates.

An elongated extension 44 on the casing 10, being hollow along the medial axis thereof, supports the drive shaft 46 for rotation. A bushing 48 mounted in the extension 44 provides a bearing for the shaft 46 at the inner end thereof. The shaft 46 extends into and is aflixed to the gear 22, a bore 50 being formed therein to receive the shaft 46. A cross-pin 52 extends through the hub 54 of the gear 22 and through the shaft 46 to prevent relative rotation therebetween. Shaft 46, there fore, drives the pumping elements and carries the outer gear 22 for rotation about the centerline of the cavity 12.

The casing extension 44 has an annular cavity 56 formed therein surrounding the shaft 46. At the end of the cavity adjacent the bushing 48, a shoulder 58 having its face perpendicular to the axis of the shaft is provided for sliding engagement by a sealing member 60. At the opposite end of the recess 56, a bearing 62 is located for carrying the outerend of the shaft 46, the bearing 62 being rigidly afiixed to a cap 64 which closes the end of the extension 44. The bearing 62 has a face 66 perpendicular to the axis of rotation of the shaft 46 and in confronting relationship with the shoulder 58 at the opposite end of the recess 56. A seal 68 slidable on the face 66 is carried for rotation by the shaft 46, the engaging surface of the seal 68 being lapped with the face 66 to provide a fluid-type joint. A compression spring 79 is disposed between the sealing members 69 and 68 and biases them into their operating positions. A deformable rubber-like ring 72 is located between the sealing member 63 and the shaft 46 and is held in place by a washer 74. Similar rings 76 are located between the seal 68 and the shaft 46 and are compressed. into sealing engagement with the seal 68 and the shaft 46 by the compressive action of a spring 78 in engagement with the washers 86. The seals '76 serve to prevent leakage between the seals 68 and the shaft 46 and to frictionally drive the seal 68 so that it rotates with the shaft 46. The member 60 does not function as a seal but operates to assure the rotation of the springs and the seal 68, since the member 60 is frictionally connected to the shaft 46 by the deformable ring 72.

In operation, the pump draws liquid through the inlet port 14 and expels the liquid through the outlet port 16. This is accomplished by the change in volume of the spaces between the contact lines formed by the engagement of the teeth on the idler and the outer gear. As the gears rotate, the idler gear tooth 34 is withdrawn from the space between the outer gear teeth, which results in a cavity that fills with liquid from the inlet port 14. After the space between the teeth reaches a maximum size, the teeth on the inner gear again enter the spaces between the outer gear teeth and the liquid is forced outwardly into the outlet port 16. Since the inner gear tooth extends to the periphery of the outer gear substantially all of the fluid is removed. Thus increasing the capacity of the pump for a given size and reducing the carryover to a minimum.

It is to be understood that although the foregoing is necessearily of a detailed character, the specific terminology is not intended to be restrictive or confining and that various rearrangements of parts and modifications of design may be resorted to without departing from the scope or spirit of the invention as herein claimed.

What is claimed is:

1."A rotary pump comprising a casing including a cylindrical cavity having an inlet and an outlet port disposed adjacent each other and separated by a dividing wall having an end contiguous to said cavity, an outer rotor including a cylindrical disc mounted upon a shaft, a bearing means mounted upon said casing for rotatably supporting said shaft, outer rotor teeth disposed about the periphery of said disc and extending longitudinally therefrom, the outer surfaces of said outer rotor teeth disposed adjacent the cylindrical surface of said casing forming a wall of said cavity being constructed and arranged as arcs of circles having a constant radius substantially equal to the radius of said adjacent Wall to rotate in sealing contact relative thereto, the inner surfaces of said outer rotor teeth being shaped as arcs of circles having a constant radius, an inner rotor having teeth formed by tangent circular convex and concave surfaces, said inner rotor being rotatably mounted within said cavity in eccentric meshing engagement within said outer rotor to provide spaces between said teeth of said rotors of varying size about the periphery of said inner rotor, said outer rotor teeth being spaced from each other to provide passageways connecting said ports with said spaces between said teeth of said rotors, the number of teeth upon said inner rotor being one less than the number of teeth upon said outer rotor, said circular concave and convex surfaces of said inner rotor teeth. being shaped as arcs of circles having a constant radius, said inner circular surfaces of said outer rotor teeth having a radius of curvature slightly less than the radius of curvature of said circular concave surfaces of said inner rotor, the axis of rotation of said inner rotor being disposed along an imaginary line extending through the axis of rotation of said shaft and the center of said dividing wall, said radius of curvature of said inner circular surfaces of said outer rotor teeth and said circular concave surfaces of said inner rotor having an identical center which is disposed upon said imaginary line when said outer rotor teeth are centered upon said line, said inner rotor teeth extending at said line in tangency with and between a pair of said outer rotor teeth to the periphery of said outer rotor in sea]- ing contact with said end of said dividing wall to displace a maximum amount of fluid from the spaces between said outer rotor teeth at said dividing wall and to seal said inlet port from said outlet port, and the centers of said rotors being displaced from each other along said line a distance equal to one-half of the height of said teeth upon said outer rotor to cause said inner rotor to have every one of its teeth in suflicient sealing contact with at least one of said teeth upon said outer rotor at all times to maintain an adequate seal between said spaces between said teeth and between said inlet and outlet ports about the longer path around the peripheries of said rotors.

2. A rotary pump as set forth in claim 1 wherein the thickness of said dividing wall is less than the distance between said outer rotor teeth along said cylindrical surface of said cavity to insure that said inner rotor teeth displace :a maximum amount of fluid from said spaces between said outer rotor teeth when said inner rotor teeth are disposed between said ports.

References Cited in the file of this patent UNITED STATES PATENTS 1,682,564 Hill Aug. 28, 1928 6 Hill Aug. 28, 1928 Richer Apr. 8, 1930 Hill June 14, 1932 Pitt June 26, 1934 Weaver July 31, 1934 Pigott Sept. 8, 1936 Schirmer July 19, 1938 Eilers Nov. 24, 1942 Graef Dec. 14, 1943 Hill et a1. Oct. 16, 1945 Hill June 24, 1952 Hill et a1 June 24, 1952 Edwards Oct. 28, 1952 Hill Dec. 7, 1954 FOREIGN PATENTS Great Britain May 15, 1930 Great Britain July 5, 1933 

